Fish Toxicology- AAHM.316- Classification of poisons and types of poisoning.

1. CLASSIFICATION OF POISON and
TYPES OF POISONING
Mr. Jayanta Subhash Tiple
Assistant Professor (Contractual),
Dept. of Aquatic Animal Health
Management (MFsc),
College of Fishery Science, Udgir - 413517
Dist. Latur (MS), MAFSU, Nagpur.

2. POISON
 A poison is any substance that is harmful or destructive to a biological (living)
system.
 Poisons may be defined as “Any substance which when ingested, inhaled or
absorbed or when applied to, injected into, developed within the body by its
chemical action, may cause damage to structure or disturbance of function”.
 A poison derived from a biological source is conventionally called as a toxin.
 Forms - solid, liquid or gas which when introduced into the living body results in
ill effects or death.
 Include corrosive substances, mutagens, carcinogens, teratogens (birth defects or
congenital disorders) and harmful pollutants etc.
 A poison is a small dose is medicine and medicine in a large dose is a poison
(Taylor, 1859).

3. The ideal poison characteristics include it as
 Colourless,
 Tasteless,
 Soluble,
 Exotic,
 Undetectable,
 Low Dose Lethality,
 Easily Obtained,
Delayed Onset Of Action And Decompose After Death,
 Chemically Stable And Found In The Burial Environment
The ideal poisoncharacteristics :

4. Classification of Poisons – Based on source
Natural
Plants, animals
Synthetic
(Chemical)
Plants – phytotoxins, they are present
in leaves, flower (alkaloids, terpenes,
and especially phenolics,).
Animals – Zootoxins - poisonous
animals like snakes, insects,
amphibians some fish like puffer fish
etc.- self-defense when
verrucotoxin
tetrodotoxin

5. MICROBIAL SOURCES OF POISONS OR TOXINS
 Bacteria (Staphylococcus aureus, Salmonella, Clostridium perfringens, Campylobacter, Listeria
monocytogenes, Vibrio parahaemolyticus, Bacillus cereus).
 Blue green algae (Anabaena and Microcystis), dinoflagellates (Shellfish poisoning - paralytic, neurotoxic
and amnesic shellfish poisoning), golden brownalgae (Azaspiracid toxins).
Fungi (Aspergillus) etc.

6. Four main types of poisoning
 Ciguatera fish poisoning (Ciguatera poisoning is a form of food poisoning caused by eating warm water ocean
fish that have ciguatera poison (toxin).The toxin is produced by a small organism called a dinoflagellate,
which attaches to algae in warm ocean water reef areas. Ex. Gymnodinium and ceratium)
 Scombroid fish poisoning (histamine poisoning) - Scombridae family - includes tuna, mackerel (If fish are
caught in warm areas and are not refrigerated properly, a chemical called histidine, that exists naturally in man fish,
can break down to histamine which causes symptoms within a few hours of eating the fish.)

7.  Shellfish poisoning (Some organisms present in seawater and ingested by shellfish may produce a
toxin. algal blooms or ‘red tides’).
Paralytic Shellfish poisoning (saxitoxin) Neurotoxic Shellfish poisoning (brevetoxins)
Amnesic shellfish poisoning Diarrhetic shellfish poisoning (Dinophysis)
(caused by consumption of shellfish that
contain the marine biotoxin called domoic acid.)

8. Rudderfish (Centrolophus spp.) poisoing/Escolar diarrhea
(diarrhoea)
(This is caused by eating fish belonging to the escolar and oil fish
groups. These fish have a high wax ester (oil) content. In humans, these
wax esters cannot be digested and may accumulate in the bowel
causing oily diarrhea).

9. Mineral source includes various metals and non-metal elements and their salts
and compounds etc.
 Heavy metals such as mercury (Hg), Manganese (Mn), Lead (Pb),
Cadmium (Cd), Nickel (Ni) and Arsenic (As) and their compounds
are harmful to fish.
 The heavy metals and non-metals damage the vital organ by
interacting with various enzymes and accumulated in the muscle of
fish which are transferred to higher fish eating animals.

10. Classification of Poisons- Mode of action
I) Corrosives
 Inorganic acids (hydrochloric acid, sulfuric acid)
 Organic acids (oxalic acid, carbolic acid, acetic acid, salicylic acid),
 Vegetable oils (hydrocyanic)
 Alkalies (carbamates of sodium and potassium, caustic soda, caustic potash)
II) Irritants
 Inorganic having metallic (arsenic, antimony, copper, lead, mercury, zinc etc.)
or non- metallic (phosphorous, chlorine, iodine, boron etc.
III) Neurotoxin
 Poison- have a cerebral or spinal effect
 Pesticides, plant extracts or some other chemicals that affect the brain

11. IV) Cardiovascular
Poison - Affect blood, heart, blood vessels. Eg. Anticoagulants, Cardiotoxic and
Asphyxiant poison like Oleander, Nicotine etc.
V) Respiratory depressants
Which comprise of poisonous gases like carbon monooxide (CO), coal gas, excess
carbon dioxide (CO2), ammonia, hydrogen sulfide in water etc.
VI) Miscellaneous
Poison go into the water bodies by surface runoff and these poison include drugs
and antibiotics used in higher animals as well as in fishes- at high concentrations
Further on the basis of mode of action, the poison are divide into the ones having

12. Local effect: Poison that affects the local tissue or organ on which it contacts
like irritation of the skin by corrosives or by other chemicals on eyes
Systemic effect: Poison that affects one or more organ system by circulating
through the blood. Eg. Different chemicals affect the circulatory system, nervous
system of fish etc.
Combined effect: Poison have both local and systemic effects Eg. Carbolic and
Oxalic acids, Phosphorous etc.

13. Based on the relative toxicity of poison:
The poison can be classified into
 Extremely toxic, which can be fatal to animals at a very low dosage (in
microorganism),
 Highly toxic (produce toxicity at 1 mg to 50 mg)
 Moderately toxic (toxic at 50-500mg) and
 Non-toxic (produce toxicity at very high toxic dose(more than 15
g/kg) Radiation from different sources are also defined as poisons
 The relations can be from manmade or natural sources and upon contact with
the living organisms, they changed the DNA base paring which results in the
faulty protein, cancer and ultimately death
 Common examples of radiations are X rays, cosmic rays, radioisotopes etc.

14. CLASSIFICATION OF POISON-Based on their toxic effects in the body as:
Poisons which cause death by anoxia
Poisons which make haemoglobin incapable of transporting
oxygen
e.g. Carbon monoxide, nitrites
Poisons which desroy haemopoitic organs
e.g. Radioactive substances
Poisons which damage protoplasm or parenchyma. These poisons produce local irritation
and after absorption cause
damage to the cells and Capillaries
e.g. Phosphorus and carbon tetrachloride
Poisons which affect the nerve cells and fibres
e.g. Hypnotics, Narcotics, Anesthetics, Alcohol, some Alkaloids and Glycosides

15. Based on their chemical and physical nature as
 Organic poisons
 Inorganic poisons
 Gaseous poisons
 Nitrogenous
 Non-nitrogenous organic poisons etc.
Based on their behaviour during separation procedures as
 Volatile poisons
 Non-volatile organic poisons isolated by solvent extraction
 Metallic poisons and
 Miscellaneous poisons.

16. GUIDELINES FOR THE CLASSIFICATION OF POISONS BASED ON THE
DOSE
Extremely toxic <1mg/kg
Highly toxic 1-50 mg/kg
Moderately toxic 50-500 mg/kg
Slightly toxic 0.5-5 g/kg
Practically non toxic 5-15 g/kg
Relatively harmless > 15 g/kg

17. The following is a list of types of poison by intended use:
 Avicide – substance which can be used to kill birds
 Biocide – a chemical substance capable of killing living organisms, usually in a selective way
 Fungicide – a chemical compound or biological organism used to kill or inhibit fungi or fungal
spores
 Microbicide – any compound or substance whose purpose is to reduce the infectivity of microbes
 Germicide – a disinfectant
o Bactericide – a substance that kills bacteria
o Viricide – a chemical agent which "kills" viruses outside the body
 Herbicide – a substance used to kill unwanted plants
 Parasiticide – any substance used to kill parasites
 Pesticide – a substance or mixture of substances used to kill a pest
 Acaricide – pesticides that kill mites
 Insecticide – a pesticide used against insects
 Molluscicide – pesticides against molluscs
 Nematocide – a type of chemical pesticide used to kill parasitic nematodes (roundworms)
 Rodenticide – a category of pest control chemicals intended to kill rodents

18. Factor affecting the toxicity of poison
Biotic factors
 Taxonomic group of which an animal belongs.
 The aquatic bioassays indicate that arthropods are more sensitive to poisons than fish and later
are more sensitive than amphibians to toxicants.
 Algae, macrophytes are less sensitive than other aquatic animals.
 Age and body size of fish
 Larval stage of fish are is considered to be the sensitive than the adult stage
 The egg stage considered to be most resistant due to the membrane coverings that protect it from
reacting to the available poison in theenvironment
 The small organism are more sensitive to the toxoids because of having more surface area:
volume ratio, which leads to fast chemical uptake per unit weight

19. Abiotic factors
The most common abiotic factors that affect the toxicity of poison are
 Temperature
 pH
 Alkalinity
 Salinity
 Hardness.

20. Temperature: Increase the metabolism which in turn reflects
 The respiratory rate
 Chemical absorption
 Detoxification
 Excretory rate and all of which may affect the toxicity of a chemical or poison.
 Cytochrome P450 an enzyme used for the metabolism of toxic substances is
greatly influenced by environmentaltemperature.
 It was shown that Oryzias latipes exposed to diethynitrosamine developed a
few liver tumour at cold temperatures than at higher temperatures.

21. pH and Alkalinity:
pH promptly influence the toxic effects of different chemicals or other poisons on
aquatic organism.
 Hydrogen ions - very acidic conditions -increasesthe permeability of the gill
epithelium thereby causing the loss of important electrolytes and ultimately affect
the osmoregulation.
 Toxicity of trace metals are highly influenced by pH, it affects the chemical
separations in water or competes with metals for sites on biological membranes.

22. TYPES OF POISONING
Acute
 Acute poisoning is associated with exposure to a relatively large, often
single, dose of a toxic agent, this being followed by rapid manifestation of
more severe clinical signs of intoxication.
 It is also defined as sudden violent syndrome caused by a single large dose
of poison.

23. Sub-Acute
 In sub-acute poisoning the exposure level is lower and the survival time longer,
than in acute poisoning, but the period between exposure and manifestation of
signs of poisoning and possible death is again relatively short.
 Symptoms of toxicity develop gradually.
 Low doses of poisons are administered for a period of 90 days.
 No Observed Effect Level or No Observed Adverse Effect Level and to identify
the specific organ(s) affected by the test compound after repeated
administration.

24. Chronic
 Chronic poisoning is usually caused by multiple exposures to the poison, while
individual quantities are not sufficiently large to produce clinical intoxication.
 It is also defined as persistent lingering condition brought about by small repeated
doses.
 A relatively long delay is observed between the first exposure to the toxic agent and
the eventual development of signs of poisoning.
 In the chronic toxicity studies, the exposure time is six months to two years for
rodents and one year for non-rodents.

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